Radiation therapy has a long history of providing increased local and regional control of disease when used after surgery for malignancies of the brain, head & neck, lung, breast, stomach, pancreas, colon, rectum, uterus, cervix, prostate, skin, esophagus, kidney, bladder, ovary and soft tissues (sarcomas). Intraoperative radiotherapy (IORT) is a subspecialty in which the radiotherapy is given at the time of surgery. Its primary advantage is the ability to surgically remove organs-at-risk from the post-operative field during treatment, enabling higher doses to be given safely. IORT has been in use for many years at specialized facilities and has a wealth of clinical data to support its safety and efficacy.
Two concomitant developments have created an opportunity to overcome the current limitations of IORT. One is the development of electronic brachytherapy. A catheter-based radiotherapy system that produces ionizing radiotherapy from a very small source. It can effectively achieve desired radiotherapy fields that were previously created with seed-sized isotopes. Its treatment energy is low enough that expensive shielding is not required, and as it is not radioactive (when the machine is off), expensive procedures and protections are not required.
The second development is surgical robotics. A success story developing over the previous decade, surgical robots have facilitated more and more minimally invasive procedures, including oncologic resections. The rapid recovery time and shortened hospital stays have been well-received in all applications. Prostatectomies and hysterectomies comprise the majority of oncologic surgeries, though this is evolving. Patients are evaluated for post-operative radiotherapy in the same manner after either a robotic or traditional resection.
Applicators for manipulating radiation delivery catheters or seed-sized isotopes have been developed for use in IORT in a very precise, controlled and “real time” environment. Such applicators need to be very stable and not vulnerable to perturbations while being manipulated in the operative theater.
Treatment of irregular surfaces, anticipated to be a common condition for treatment, requires careful planning and precise localization of the applicator to cover a target surface of a tissue with a uniform dose distribution. Prior to treatment, precise measurements are obtained to determine the distance from each source position within the applicator to the intended target surface. A map of the irregular surface is thus rendered, and a treatment plan is calculated with this data. No movement of the applicator is permitted between when the measurements are obtained and when the treatment is given, a period of time that may last between 15-30 minutes.
It would therefore be advantageous to have a minimally invasive applicator which can be firmly secured in a durable, immobile position for both planning and treatment.